Episode list

Josie, faced with the revelation that Avenir is her father and the true villain behind the events at Blake Holsey, becomes upset and turns to Professor Z for advice. When Marshall visits from his new school for everyone's graduation, the Science Club, save Vaughn, are reunited again. At Victor's house, Josie opens the device with Sarah's message detailing specific instructions that will allow them to stop Avenir from achieving his goal at last; having learned about different alternate universes, he intends to control each universe. Josie and Vaughn are forced to confront one another as Avenir tries attain control of the universe, but ultimately fails and disappears while Sarah Pearson finally returns to the timeline. With the wormhole destroyed, the Janitor is trapped, but grateful that Josie has stopped Avenir for good.

Josie's clone and the Janitor reveal to Lucas and Professor Z that the original Josie is trapped in an alternate timeline where she is the only inhabitant. Realizing she can't replace Josie on Earth, she decides to replace her in the alternate dimension.

A year after Josie steals the Chi ball from Victor, he is in ruins and a man named Avenir is chairman of the board and plans to close the school after the students graduate. Vaughn, estranged from Victor, quickly becomes part of Avenir's plans. In the Science Club, Lucas becomes increasingly obsessive with finding Josie, who reappears suddenly from the wormhole. However, she is quickly exposed as Josie's clone when she realizes that she is unable to open Victor's device to receive Sarah Pearson's message.

Vaughn is helping Lucas with an E.E.G. experiment. A circuit board blows, resulting in Lucas' personality moving into Vaughn's body and Vaughn's moving into Lucas' body. They learn about what its like to be each other and the Science Club has to straighten out the mess. Also Josie and Lucas do a scene from Romeo and Juliet.

A clone of Josie is created from the saliva on her chewing gum. This causes problems in her already distant relationship with her mother.

Josie experiences sleep deprivation and it causes her to wig out, until she realizes Vaughn is the key to the problem.

After an argument, Josie's intelligence transfers to Vaughn faster every minute, to the point where Josie is on the verge of collapse and Vaughn rebuilds a cold fusion reactor for his father. Meanwhile, Josie's clone returns the floating Qi ball to Victor.

When Victor asks Vaughn to spy on the Science Club, Vaughn's emotions manifest themselves in a series of localised storms, which can only be resolved when he releases all the pressure inside him by defying his father, and telling the truth about Josie's stolen journal.

When Marshall writes a prediction column for the school paper, he neglects to proofread his work and "Someone will diet" turns into "Someone will die." Things get scary when Marshall's predictions start to come true.

When Corrine auditions for Magnet 360 (Marshall's band) as a singer, she looks at an antique mirror, through which she travels. Everyone there is opposite (for example, Vaughn, the athlete, is a bookworm) and everything appears as a mirror image (i.e. whenever she would normally, say, go left, now she must go right). To return, Corrine must learn to use the creative half of her brain without losing her ability to use her logical side.